This application claims the benefit of Belgian Application No. 2001/0276 filed Apr. 20, 2001.
This invention relates to a device for presenting weft yarns to two rapiers provided above one another of a rapier weaving machine, comprising two yarn carriers, which are movable between a receiving position in which they are able to receive a respective weft yarn to carry along this yarn and a presenting position in which they are able to present a yarn carried along to a respective rapier to insert this yarn into the shed.
After having inserted two weft yarns into a shed between the warp yarns of a rapier weaving machine the inserted weft yarns are beaten up by the weaving reed. The weft yarns are then cut through along the selvedge of the fabric, so that the weft yarns supplied will obtain free ends. During a next yarn weft, each rapier must be able to insert a new piece of weft yarn into the shed, and therefore the free weft yarns must be taken up at the selvedge of the fabric after each weft and presented to the rapiers for a next weft.
More particularly, this invention relates to a device for taking up the two free weft yarns at the selvedge of the fabric and for presenting them for a next weft, after the beating up of the weaving reed and after cutting off the inserted pieces of weft yarn. More particularly this invention relates to such a device that at the same time provides for automatic gripping, cutting off and presenting two weft yarns to the rapiers.
In the Belgian patent disclosure BE 1 008 211 a similar device has been described. This device is provided for successively gripping, cutting off and presenting to an upper and a lower rapier two weft yarns that were inserted into a fabric on a double rapier weaving machine. When the weaving reed starts beating up, the inserted weft yarns are well spread by means of weft separation plates and inserted into the respective opened weft cutter-gripping combinations. After cutting through the weft yarns, relatively long weft yarn ends will appear at the selvedges of the fabric when using this device. In order to remove these long yarn ends, additional waste selvedges are provided along the selvedges of the fabric. Thereafter, these waste selvedges are cut off and removed. This is a cause for waste of weft and warp yarn material. This weft presenting device is attached to the weaving batten, and therefore moves together with the weaving batten, so that the inertia of this device causes additional inertial forces on the weaving batten. This is especially harmful at high weaving machine speeds.
Another device for gripping, cutting off weft yarns and presenting them to the rapiers situated above one another of double rapier weaving machines is described in DE AS 2 258 597. This device is not installed on the weaving batten, but has likewise the disadvantage of producing relatively long weft yarn ends at the selvedges of the fabric and likewise requires the use of waste selvedges. Moreover, the drive with open cam system and resetting force by means of a retracting spring prevents the weaving machines from reaching high speeds.
The purpose of the present invention is to provide a device for presenting weft yarns to two rapiers situated above one another of a rapier weaving machine, by means of which the above-mentioned disadvantages are remedied.
More specifically, the present invention aims at providing a device with which the weft yarns may be taken up and cut off as close to the selvedge of the fabric as possible, in order to obtain weft yarn ends which are notably shorter than when using the known devices (so that the use of waste selvedges is no longer required), and with which the yarns that are cut off may then be presented to two rapiers situated above one another.
This purpose is attained by providing a device for presenting weft yarns to two rapiers provided above one another of a rapier weaving machine, comprising two yarn carriers that are movable between a receiving position in which they are able to receive a respective weft yarn in order to carry along this yarn and a presenting position in which they are able to present a weft yarn carried along to a respective rapier to insert this weft yarn into a shed, each yarn carrier being carried by a respective presenting arm and these two presenting arms being rotatable above one another in respective intersecting planes of movement.
Because the two planes of movement of the rotatable presenting arms are no parallel planes, but intersecting planes, the yarn carriers in the receiving position can be situated above one another at a limited distance and being rotated, moving away from each other, towards the presenting position, so that in that presenting position they reach a vertical intermediate distance corresponding to the difference in height between the two rapier levels. Because of this, the yarn carriers can reach the fell of the fabric at a short distance above one another and the weft yarns can be gripped at a height, which is only slightly different from the height at which they extend in the fabric. Because of this, spreading the weft yarns well is not needed. Because of this limited spreading the yarn end between the selvedge of the fabric and the weft cutter can be particularly short. In other words, the weft yarns can be cut off very short at the selvedge of the fabric and thus very short weft yarn ends can be obtained and the use of waste selvedges can be avoided.
In a preferred embodiment the upper presenting arm is rotatable in a practically horizontal plane of movement, whereas the lower presenting arm is rotatable in plane of movement inclined downwards in the direction of the presenting position. When the lower presenting arm rotates towards the position in which the yarn carrier comes in its presenting position (in the following this is called the presenting position of the presenting arm) the yarn carrier moves, slanting downwards, until just below the level of movement of the lower rapier in order to present the lower weft yarn in a very efficient manner to this lower rapier. The upper presenting arm can stay in a same horizontal plane, which extends just below the level of movement of the upper rapier, in order to present the weft yarn in a very efficient manner to the upper rapier. Of course, other arrangements are also possible, for instance an arrangement in which the plane of movement of the lower presenting arm is practically horizontal and the plane of movement of the upper rapier is inclined upwards in the direction of the presenting position, or an arrangement in which the planes of movement of the upper and lower presenting arms are inclined upwards and downwards respectively in the direction of the presenting position.
In a particular embodiment, the two presenting arms are attached rotatably to a vertical shaft, while at least one of the presenting arms is attached to this shaft by means of a bearing with a rotation plane that is inclined upwards or downwards to the presenting position.
In a particularly advantageous embodiment the presenting arm comprises a yarn guiding means for a weft yarn, which is provided at a higher level than the yarn carrier, so that each presenting arm can be brought into a position in which the yarn carrier keeps a weft yarn, carried along, below the carrying level of a rapier, while the yarn guiding means keeps the weft yarn, carried along, above this carrying level. In a similar manner, presented weft yarns may be easily and impeccably carried along by the rapiers. The rapier head can move between the upper feed-through eye and the lower yarn carrier to take up the weft yarns by means of the rapier head when the presenting arm has taken up its presenting position.
If the yarn guiding means of each presenting arm is provided on the presenting arm, the advantage is obtained that the feed-through eyes remain at a constant distance from the weft yarn grippers during the rotating movement, because of which the weft yarns presented always remain tightened and the weft yarns can be taken up well by the rapier heads.
In another preferred embodiment the device comprises a separating body with separating means to keep separated two weft yarns inserted into a fabric above one another at the fell of the fabric, while the separating body comprises a first part, in essence, running in the warp direction, which is connected to the separating means via a second part approaching the fell of the fabric in the direction of the separating means, so that the separating means are situated closer to the fell of the fabric than the first part of the separating body.
A similar separating body leaves open a free space next to the first part on the side directed towards the fabric, while the separating means may be situated very close to the fell of the fabric and will leave space for the yarn carriers. In an advantageous manner, this space can be occupied by other parts of the device of the weaving machine. Preferably, the position of the separating body is also adjustable.
A very suitable device is obtained by providing a weft cutter to cut through the said weft yarns, so that this weft cutter, in essence, is situated next to the first part of the separating body on the side directed towards the fabric. Thus, the weft cutter can be situated very close to the selvedge of the fabric in order to cut through the weft yarns as close as possible to the selvedge.
Preferably, the yarn carriers mentioned above are carried out as gripping devices, which may be brought into an open or a closed situation by an actuator.
The device functions very well when the yarn carriers can be positioned in their receiving position such, that two weft yarns inserted into the fabric above one another are brought into an opened yarn carrier by the beating up of the weaving reed.
It is further also preferable to carry out the device with a module made in one piece, which comprises one or more of the following components: a separating body in order to keep separated at the fell of the fabric two weft yarns inserted into the fabric above one another, a weft cutter for cutting through the weft yarns along the fell of the fabric, an upper and a lower yarn carrier on a respective rotatable presenting arm in order to present the weft yarns, after they have been cut through, to respective rapiers, and driving means for the device.
The said driving means can be comprised in a casing, which is a part of the said module, this casing functioning as a carrier for the various components of the module.
When the said module is movable and adjustable in the weft direction, the great advantage is obtained that the adjusted synchronizations and positions can be maintained when adjusting the weaving width or when making any adjustments in the weft direction. Adjusting can be achieved in one single operation for all components being part of the module.
The said module can also be connected to a temple device, the position of which is adjustable in the weft direction, the connection being realized with the help of a coupling means, by means of which the mutual distance in the weft direction between the temple device and the said module is adjustable. Such an adjustable coupling means is, for instance, a spindle adjusting screw.
By coupling the temple plates with their holder to the module of the weft yarn presentation, the temple holders will be prevented from hurting the weft cutter when adjusting the temple width. When adjusting the temples widthways the adjusted minimum mutual distance between weft cutter and temple holder plate can also be maintained. Adjusting the temples widthways and adjusting the weft presentation may be done in one operation. To that effect, the weft presenting module and the holder of the temple device are, for instance, connected to one another by means of a spindle screw with left-hand and right-hand thread. The mutual distance between temple device and weft presenting module can be adjusted with precision and can also be maintained. Because of this adjusting widthways becomes less time-consuming and possible damage to the weft cutter will be avoided.
These and other characteristics of the device according to the present invention are clarified and illustrated in the more detailed description of a possible embodiment following below.
It may be clear that the only purpose of this description is to clarify the invention with the help of some examples and therefore in no way may be considered as a limitation of the scope of this patent protection, such as it will be determined in the attached claims.
In this description reference is made by means of reference numbers to the attached drawings, of which: